Calcitonin salmon is a man-made version of the hormone calcitonin that is found in salmon.

The reviewers said significant questions remain about calcitonin salmon's effectiveness in reducing fractures in the treatment of postmenopausal osteoporosis.

An advisory panel to the FDA is scheduled to discuss the products on March 5 and will make a recommendation to the agency on whether to allow the continued marketing of these products for that use.

Last July European regulators recommended that long-term use of calcitonin be curtailed after a review found evidence of a small increased risk of cancer with long-term use of the drugs.

They recommended that they should only be authorized for short-term use in Paget's disease, a bone disorder; for acute bone loss due to sudden immobilization; and for excess calcium in the blood caused by cancer. They ruled that the benefits of calcitonin-containing medicines did not outweigh their risks in the treatment of osteoporosis and that they should no longer be used for this condition.

Unigene officials declined to comment on the FDA staff review as they do not distribute a calcitonin product in the United States. Upsher Smith officials were not immediately available for comment. Novartis said in a statement that it "places the highest priority on patient safety and the appropriate use of its medicines and is looking forward to the opportunity to engage in the discussion at the upcoming meeting."

Unigene shares were down 20.65 percent at $0.12 on the pink sheets. Novartis shares were up 1 percent.